Recent studies indicate that several classes of memory deficits in animals are reversible. The proposed research focuses on determining internal and external conditions which alleviate the memory loss produced by an amnestic treatment (retrograde amnesia) or by maturation of the organism (infantile amnesia). Since many reactivation treatments have only a transient effect, a major objective is to delineate conditions necessary for a more permanent recovery of memory. The proposed experiments will provide information necessary for evaluating the role of storage/encoding and retrieval variables in retention loss.